An example a of a conventional speaker is shown in FIGS. 5 and 6.
In the speaker a, required components and members are supported by a frame b. That is, the outer periphery of a diaphragm c is supported at a front end face of the frame b with an edge d therebetween. A voice coil is connected to the inner periphery of the diaphragm c with an unshown bobbin therebetween, and a magnetic circuit section for forming a magnetic field necessary to drive the diaphragm, that is, the voice coil is supported by the frame b.
A flange portion e is formed at the front end of the frame b to serve as a mounting portion projecting toward the center, and the edge d is supported on the front face of the flange portion e by, for example, bonding. A gasket f is mounted by, for example, bonding outside a portion of the front face of the flange portion e in which the edge d is supported.
When the speaker a is mounted at a predetermined mounting position, the frame b is fixed at its rear end, and the gasket f at the front end is abutted on a predetermined portion.
In the above-described conventional speaker a, both the edge d and the gasket f must be mounted on the front face of the flange e formed at the front end of the frame b. Therefore, a space in which the gasket f is mounted must be formed outside the portion in which the edge d is mounted. For this reason, the width L of the flange is increased. That is, the outer diameter of the front end of the frame b is increased by a length corresponding to the space in which the gasket f is mounted.
The maximum size of a speaker to be mounted in a limited space, for example, the interior of a car, is limited. For example, in a case in which the space in which the front end of the speaker is placed is limited, the size of the front end, that is, the outer diameter of the front end is limited.
In the above conventional speaker a, the maximum outer diameter of the front end of the frame b is limited by the condition of the space for the mounting portion. A mounting face for the gasket f must be provided outside a mounting face for the edge d on such a condition, and therefore, the outer diameter of the diaphragm c must be reduced by a length corresponding to the mounting face for the gasket f.
The characteristics of the speaker greatly depend on the size of the diaphragm. As the size of the diaphragm increases, the frequency characteristic is improved, the sound pressure is improved, and as a result, the sound quality is improved. In the above conventional speaker a, however, since the gasket f and the edge d are mounted on the same flange e, the outer diameter of the diaphragm c must be reduced to ensure a mounting face for the gasket f.
Accordingly, an object of the present invention is to use, in a speaker whose maximum outer diameter is limited, a diaphragm that is large for the outer diameter.